The wet weather is expected to continue, with “very heavy and persistent” rain across parts of the UK on Wednesday, the Met Office has said.
A yellow warning for rain will come into force between 9am and 10pm on Wednesday covering western areas of Scotland.
It comes after more than 200 people were evacuated in West Sussex on Tuesday after the River Arun burst its banks.
They included about 180 people rescued overnight from Medmerry Holiday Park in Earnley and about 15 from Ferry Road and Rope Walk in Littlehampton, West Sussex County Council said.
One person showing signs of hypothermia was taken to hospital.
Residents described the flooding as “scary and unprecedented”.
Forecasters said heavy rain would continue to batter parts of the UK on Wednesday, particularly Northern Ireland, northwestern England and western areas of Scotland, but much of central England and Wales will experience a milder day.
Met Office meteorologist Annie Shuttleworth said: “Most areas are going to feel on the chilly side to start the day (on Wednesday).
“There will be a good deal of sunshine particularly across eastern areas through the morning, the South East seeing the longest-lived sunshine tomorrow morning, but across the West it’s really going to deteriorate through the day.
“Some very heavy and persistent rain will push through Northern Ireland into northwestern England and western areas of Scotland – that’s where there is a rain warning in force.
“There could be 60mm of rain falling through the day on Wednesday.”
She continued: “Further south across much of central England and Wales and the South Coast too it will be a much cloudier afternoon.
“There will be some rain from time to time but I think if you’re away from the West and from coastal areas, rain will be fairly limited and it’s actually going to be a significantly milder day tomorrow with this southerly wind bringing with it this mild air.”